Apparatus for connecting the ends of submerged pipes

ABSTRACT

The ends of submerged pipes are connected using a receiver provided with two apertures through which the pipe ends extend, the receiver being adapted to form a watertight enclosure with an intervention unit and housing means for closing the ends of the pipes comprising two stoppers bearing seal means to be applied against the inner walls of the pipe ends and being maintained spaced apart by a first boom, the receiver including means for supporting a sleeve to be connected to the ends of the pipes and a replacement boom located in the sleeve, the connection being performed by introducing the ends of the pipes to be connected into the receiver through the apertures, at least one of the pipe ends being introduced by movement of the receiver relative thereto, closing the ends of the pipes with the stoppers, causing an intervention unit to descend on to the receiver, providing a watertight enclosure therewith, removing the water from the enclosure and placing it under atmospheric pressure, placing the receiver under hydrostatic pressure, remotely controlling the sleeve supporting means to place the sleeve in position between the pipe ends and to simultaneously replace the first boom by the replacement boom, removing the water from the enclosure and again placing it under atmospheric pressure, connecting the ends of the sleeve to the pipe ends, placing the receiver under hydrostatic pressure and withdrawing the intervention unit.

This is a Division of application Ser. No. 750,315, filed Dec. 14, 1976,now U.S. Pat. No. 4,068,491 granted Jan. 17, 1978.

The invention relates to the connection of the submerged ends of pipesor sections of pipe by butting and welding a sleeve thereto.

The need for connecting sections of submerged pipes may occurparticularly where it has become necessary to cut out a defectiveportion of an already submerged pipe, in order to substitute for it anew section, or where two portions of one and the same pipe line arebeing assembled and submerged simultaneously by means of two bargesbeing guided towards one another and where the ends of the two submergedportions must be connected together.

One method already advocated for connection of pipe ends by means of asleeve, lowered from the surface by means of an intervention unit,comprises, after having cut off the ends of the portions to be connectedto provide a suitable length gap therebetween, aligning the cut pipeends by means of an appliance known as an aligner. This appliance inaddition enables the cut ends of the pipes to be introduced intocorresponding apertures in a common receiver which is made watertight bycapping it with an intervention unit and equipping each of the twoapertures with suitable watertight seals. If each pipe end is inaddition provided with a stopper, it is sufficient to let a crew ofoperators go down in the undersea intervention unit to proceedimmediately with the connection, after having emptied the receiver ofwater and replaced the water with air at atmospheric pressure.

However, as soon as the depth at which connection is carried outincreases, the forces exerted by the hydrostatic pressure rapidly becomeconsiderable and in order to ensure perfect safety of the interventionpersonnel, it is necessary to prevent any movement of the stoppers atthe time the receiver is placed under atmospheric pressure. For thispurpose booms are employed to keep the stoppers apart.

The personnel thus being safe from any risk of entry of water byinsufficient blocking of movement of the stoppers during the whole timethat the receiver is at atmospheric pressure, proceed with theintroduction of the connecting sleeve between the ends of the pipes.This introduction, is, however, tricky because it necessarily involvesmovement of the originally installed booms. Hence it is arranged so thatduring the course of placing the sleeve in position only one boom ismoved at a time. Besides these precautions, it is still necessary toensure perfect putting in that the booms are placed in exactly the rightpositions, which increases the difficulty of connection withoutincreasing the safety of the manoeuvre.

It is an object of the present invention to provide a method ofconnection of two pipe ends using a receiver which is renderedwatertight and by means of a sleeve which is butted against the ends ofthe pipes introduced into the receiver and welded thereto by anintervention crew, wherein the introduction of the sleeve between thepipe ends is carried out while the receiver is under hydrostaticpressure.

Thus contrary to previous methods where at least one boom was necessaryto ensure the stability of the stoppers during the whole of theoperation of placing the sleeve in position it is possible by use of thepresent invention to withdraw any safety boom previously provided whenthe receiver was placed under atmospheric pressure and to substitute forit another boom after the sleeve has been placed in position and beforeatmospheric pressure in the receiver is restored to enable welding ofthe butted sleeve.

It is another object of the invention to facilitate restoration of thereceiver to a condition of perfect safety by automatic substitution of areplacement boom for the original boom during introduction of theconnecting sleeve between the pipe ends.

Such an operation is in fact made possible since the boom or booms areno longer subjected to the forces of compression resulting from thedifferences in pressure between the areas of the stoppers inside andoutside the receiver as in the former method.

It is another object of the invention to provide a movable structure forputting the sleeve into position and for simultaneous substitution of areplacement boom inside the sleeve for the original boom external to thesleeve.

Thus a simple conventional remote control is sufficient to obtain, forexample, by simple pivoting of a movable structure carrying the sleeve,and a replacement internal boom and connected to the external boomoriginally located between the two pipe stoppers, the placing inposition of the sleeve between the pipe ends and the substitution of thereplacement boom for the boom originally holding the stoppers spacedapart. The new boom is centred automatically between the two stoppersduring the course of introduction of the sleeve between the ends of thepipes, so that atmospheric pressure may then be restored in the receiverwith complete safety and the operation of welding proceeded with.

It is another object of the invention to ensure, from the first time thereceiver is placed under atmospheric pressure, an even distribution ofthe pressures exerted on the faces of the stoppers by automaticallyplacing the two pipe ends in communication upon putting the receiverinto position.

Variations in temperature and pressure may therefore occur in one of thepipes without bringing about an increased thrust against the stopper ofthe other pipe by way of the boom.

It is another object of the invention to ensure maintenance ofcommunication between the two pipe ends during the course of exchangingthe booms and placing the sleeve in position so that it is sufficient torestore atmospheric pressure in the receiver to enable the operators toundertake any work immediately under conditions of safety have beenestablished.

The invention will be more fully understood from the followingdescription of an embodiment thereof, given by way of example only, withreference to the accompanying drawings.

In the drawings:

FIG. 1 is a diagrammatic representation in elevation of the lowering ofa pipe section for replacement of a portion of a submerged pipe equippedwith a receiver in accordance with the invention;

FIG. 2 is a diagrammatic representation similar to that of FIG. 1 afterjoining of the receiver onto one of the portions of pipe;

FIG. 3 is a section of pipe for substitution equipped with tworeceivers;

FIG. 4 is a diagrammatic view of the receiver of FIG. 3 partially insection along the line IV--IV in FIG. 3 before its joining onto one ofthe portions of pipe;

FIG. 5 is an overall view showing respectively the receiver in its topand bottom portions before and after welding of the connecting sleeve;

FIG. 6 is a diagrammatic view partially in horizontal section throughthe receiver immediately after its joining to the pipe;

FIG. 7 is a diagrammatic view of the receiver after placing of theintervention unit and preparation of the ends of the portions of pipe tobe connected;

FIG. 8 is a diagrammatic view of the receiver partially in section alonga plane perpendicular to the axis of the pipes after restoration ofhydrostatic pressure in the receiver;

FIG. 9 is a diagrammatic view of the receiver similar to that of FIG. 8after placing of the connection sleeve in position and restoration ofatmospheric pressure;

FIG. 10 is a diagrammatic view of the receiver similar to that of FIG. 5after welding of the sleeve, and

FIG. 11 is a diagrammatic view of the receiver similar to that of FIG.10 after return of the intervention unit to the surface.

As the method of connection may be applied equally to the joining of theends of two portions of one and the same pipe which is being assembledand which is being submerged by means of two barges being guided towardsone another as to the joining of the ends of a section for replacementof a portion of a pipe already submerged, it will be observed that FIGS.1 to 3 are intended to illustrate, for only one of the possibleapplications, the various structures for placing the receiver inposition, as these structures may be of any kind. In particular anappliance known as an aligner may be employed for aligning the ends ofthe submerged pipes to be connected, for cutting off of these ends so asto obtain a predetermined gap between them and for introducing them intothe appropriate apertures in the receiver for connection.

In the embodiment of FIG. 1, the receiver 15 is integral with a sledge19 upon which it can move parallel with the axis of apertures 24 forreceiving the pipes to be connected. This movement is effected by remotecontrol of jack 18, effected from the surface by means of the generalcontrol cable 25, for example. In the example chosen, one of theapertures 24 is already provided with a section to be connected to thepipe 20 and which has also been designated 20 in order to remind onethat the receiver 15 may equally well contain beforehand one of the endsof the pipes to be connected. The receiver 15 is connected by a carrierimplement 33 to a cable 26 which also supports an apparatus 27 forpositioning the free end of the section 20. Guide devices 28 and 29enable one of the ends of the sledge 19 and of the section 20 to belowered vertically straight down onto the ends of the pipes 14 and 20 bymeans of guide cables 30 and 31.

At the end of its descent the sledge 19 rests on the bottom or on asuitable flooring 34 as shown in FIG. 2. Manipulation of the supportingcable 32 and guide cable 30 enables the end of the pipe 14 to be broughtfacing the aperture 24. The pipe 14 is preferably guided laterally bythe end 35 of the sledge 19, then by a guide cone 36 at the time ofintroduction of the end of the pipe 14 into the receiver 15 by movementof the receiver along the axis of alignment of the pipe 14 and thesection 20.

It is clear that the receiver 15 may be an element isolated from anystructure such as that represented, for example, in FIGS. 1 and 2 andmay then be employed for completing the connection of the section 20 tothe pipe 20. Instead of an isolated receiver an assembly of tworeceivers 15 may be employed, which are joined by means of the section20 as shown in FIG. 3.

However, whatever the structure associated with the receiver itself, thelatter includes as shown in FIGS. 4 and 5 a first boom 3 connected ateach of its ends through flanges 8 and locking collars 60 to stoppers 1and 2. For simplification of the drawing the assembly of the flange 8and collar 60 has been designated 8 on Figures other than 5 and 11. Thestoppers 1 and 2 prior to the entry of the pipes 14 and 20 are held byretractable catches 17 bearing against a central frame 5 forming athruster for each stopper 1 and 2. The thrusters 5 formed of hollowtubes also carry scrapers 7 and a pipe stub 37 equipped with aquick-connector valve 38 for connection of flexible piping 12 to form abypass for the boom 3. Bosses 39, FIG. 5, enable either electric cables4 for the control of solenoid valves for the control of lip seals 9mounted on plates 6 integral or fast with the thrusters 5, or hydrauliccontrol channels 4 for jacks 11 which actuate valves 10 for the lipseals to pass through the thruster walls in a watertight manner. Theremote controls are carried out preferably from the surface by means ofthe general remote-control cable 25 or from an intervention unit 45,FIG. 7. When the jack 11 is controlled in one direction it rocks thelever 40 controlling the valve 10 which has the effect of emptying theinflatable chambers 41, FIG. 4, of the lip seals 9, thus causingrelaxing of the lips and their application against the inner wall of thepipe, e.g. pipe 14, facing them, as will be explained later.

The receiver 15 also comprises external lip seals 42 held apart byinflation of chambers 43.

When the receiver 15 is moved towards the pipe 14 by means, for example,of jack 18, FIG. 2, the end of the pipe 14, guided by the guide cone 36is introduced between the lip seals 9 and 42 (FIGS. 4 and 5) and thencaps the first scraper 7 before tilting the retractable catches 17which, by moving aside, free the thruster 5 of the stopper 1. Continuingits movement the receiver 15 takes up a central position with respect tothe ends of the pipes 14 and 20 (FIG. 6), cables 16 connecting thecatches 17 to a locator member 44 being intended to keep the boom 3 inthe centre of the receiver despite the thrust exerted by the pipe 14.

From the surface, the deflation of the chambers 41 and 43 holding backthe lips of the seals 9 and 42 is then caused and any suitable underseaintervention unit 45, FIG. 7, is let down onto the connection ring 46 ofthe receiver 15. The watertight door 47 of the unit 45 is maintainedclosed and the water contained in the receiver 15 and the skirt 48 ofthe unit 45 is depressurized and removed by means of a pump (not shown)controlled from the watertight chamber 49 of the intervention unit. Theseals 9 and 42 applying themselves respectively against the inner andouter walls of the pipe 14 ensure the watertightness of the receiver 15and the skirt 48 so that it is sufficient for the intervention crew todescend into the receiver which has been placed under atmosphericpressure in order to proceed with the connection of a sleeve 22, FIGS. 8to 11, which may be lowered either with the receiver 15 or with theintervention unit and which is coupled to a support 50 on a guidestructure 51 hinged on the receiver 15 at 52 and controlled by a jack23. Attachment of the sleeve 22 may be obtained, for example, by meansof collars 53 equipped with ears 54 which are joined by means ofclamping nuts. Each collar 53 comprises in addition a smaller auxiliarycollar 55 used to surround the boom 3. The hinge 52 is located so thatduring the course of the movement of the guide structure 51 under theeffect of the jack 23 a boom 56 centred axially in the sleeve 22 takesup the position which the boom 3 had, the latter then taking up theposition shown in FIG. 9.

Thus the intervention crew having removed the cables 16 and theattachment member 44 which has become unnecessary, mount the sleeve 22in its collars 53 or, as the case may be, check the mounting of thesleeve 22 as well as the attachment where necessary of the collars 55 tothe boom 3, FIG. 8. They proceed first of all to cut off of the ends ofthe pipes 14 and 20, if necessary, the crop ends from which have beenrepresented diagrammatically by 61 in FIG. 7, so that the separation ofthe ends of the pipes to be connected is adjusted to the length of thesleeve 22. The crew then fixes round the pipe ends to be connected,collars 21 provided with lower fingers 57 extending parallel with theaxis of the pipe and upper pivoting fingers 64 intended to facilitatepositioning of the sleeve 22 with a view to its welding to the ends ofthe pipes 14 and 20.

Before putting the sleeve 22 in position the intervention crew connectsthe ends of flexible piping 13, FIG. 5, identical with the flexiblepiping 12 and passing through the sleeve 22, to the connections onvalves 58 mounted on the pipe stubs 59 on the stoppers 1 and 2. Havingopened the valves 58 and closed the valves 38, the flexible pipe 12 iswithdrawn as well as the locking collars 60 of the flanges 8 of thestoppers 1 and 2 and the boom 3. This withdrawal involves no riskbecause of the heavy pressure exerted by the thrusters 5 of the stoppers1 and 2 on the boom 3.

The replacement boom 56 is identical with the first boom 3 and iscentred in the sleeve 22 by means of the scrapers 62. After theintervention crew has moved back into the chamber 49 of the unit 45 andthe door 47 has been closed, the watertight receiver 15 is againflooded. The jack 23, FIGS. 8 and 9, is then operated in order toreplace the first boom 3 by the boom 56 as the sleeve 22 comes to restagainst the fingers 57.

That is, the boom 3 being no longer subjected to the high pressureexerted by the thrusters 5 of the stoppers 1 and 2 since the pressuresexerted on the opposite faces of each stopper are again identical, theboom 3 may easily be removed by the collars 55 integral or fast with thesupport 50 moved by the jack 23. Hence it is sufficient that thecentering of the new boom 56 inside the sleeve 22 is correctly obtainedby means of the scrapers 62 for the flanges 8 of the thrusters 5 of thestoppers to again face the corresponding flanges of the boom 56. Withthe sleeve 22 automatically centred because of the movement defined bythe pivot 52 of the support 50 and the positioning fingers 57, thereceiver 15 may again be emptied without risk of movement of thestoppers 1 and 2. In short, the same conditions as previously againprevail, the boom 56 being compressed by the thrusters 5, and the pipe13 preventing any difference in pressure across the stoppers 1 and 2which could cause movement of the boom 56, thrusters 5 and stoppers 1,2.

The intervention crew may therefore descend again into the receiver 15,proceed, by direct manipulation of the sleeve 22 and/or the fingers 57and 64 or any other means, to accurately adjust the distances betweenchamfers on the ends of the pipes 14, 20 and the sleeve 22, and finallycarry out the welding of the sleeve 22 to the pipes in complete safety.The intervention crew then returns to the unit 45 and, if necessary,controls by means of a remote control the reinflation of the chambers 41for raising the lips of the lip seals 9. However, in view of thepressure balance between the faces of each stopper, it may be sufficientto apply at the end of the pipe 14, for example, a sufficient pressureindicated diagrammatically by the arrow 63 (FIG. 11) to bring about thedischarge of the stoppers 1 and 2 and the boom 56 through the pipe 20.The boom 56 being no longer rigidly attached to the flanges 8 of thestoppers 1 and 2, the assembly can easily pass through cranked portionsof the pipe 20, the possible inclination between the axes of the boomand the stoppers 1 and 2 not being restricted by the flexible piping 13.

Although in the foregoing only one embodiment has been described ofapparatus for putting into effect the method of connection explained, itwill be understood that numerous modifications in detail may be appliedto the various means employed. Thus, for example, any structure may beemployed which enables prior cutting off of the ends of the pipes 14 and20 to avoid any cutting inside the receiver. Similarly the first boom 3may be not attached to the support 50 for the sleeve 22 but fall byitself under the thrust of the latter.

Similarly watertight seals of any other type than lip seals havinginflatable chambers for raising the lips may be employed.

What is claimed is:
 1. Apparatus for connecting two ends of submerged pipes comprising a receiver having two aligned apertures through which the pipe ends extend, jack means for moving the receiver relative to one pipe end to assist in the introduction of the other pipe into said receiver, an undersea intervention unit detactably secured onto said receiver to define a watertight enclosure for an intervention crew for connecting the two ends of the pipes by means of a sleeve, first seal means between the outer surfaces of the pipes and the apertures in the receiver, a stopper having second seal means disposed within the end of each pipe, a first boom detactably connected to said stoppers for holding said stoppers apart, a sleeve having a length equal to the gap between the ends of the pipes, a replacement boom disposed inside said sleeve, and movable sleeve support means for placing the sleeve in position between the pipe ends under remote control for simultaneous replacement of the first boom by the replacement boom while the receiver is under hydrostatic pressure to balance the pressures being exerted upon the faces of the stoppers.
 2. Apparatus as claimed in claim 1, wherein each stopper comprises a hollow central portion which forms a thruster equipped with at least one connector pipe stub.
 3. Apparatus as claimed in claim 2, wherein each pipe stub is equipped with a valve.
 4. Apparatus as claimed in claim 3, wherein each valve includes means for detachable connection to a flexible piping.
 5. Apparatus as claimed in claim 2, wherein the hollow central portion of each stopper includes two pipe stubs each equipped with a valve, and the hollow central portion ends in a flange for attachment to a corresponding flange on a first boom for bearing against the stoppers.
 6. Apparatus as claimed in claim 2, wherein said sleeve-support means is equipped with collars for attachment of the said sleeve, said replacement boom being centred in said sleeve by means of scrapers, the sleeve-support means carrying collar means for attachment to the first boom, the support means being mounted for pivotal movement for withdrawal of the first boom and the simultaneous placing in position the sleeve and the replacement boom, additional jack means for controlling the movement of the support.
 7. Apparatus as claimed in claim 6, wherein the sleeve includes flexible piping equipped with two connectors for connection to the valves on the stoppers.
 8. Apparatus as claimed in claim 2, wherein each stopper includes a first end scraper adjacent an inflatable-lip seal and a hollow conical structure connected to a hollow cylindrical portion bearing a second scraper and two pipe stubs for connection to two valves, the pipe stubs being located between the second scraper and a wall with a flange terminating the cylindrical portion. 